This study will be a controlled, stratified, randomized, multicenter, dose ranging Phase 2 trial of T-0 given to HIV-1 infected adults. The T-20 will be used in combination with abacavir, amprenavir, ritonavir and efavirenz in patients who have failed one or moo'[ re protease inhibitor containing antiretroviral regimen. Patients will be randomly assigned to receive one of three doses of T-20 by subcutaneous injection or to the background antriretrovirals alone. The study will be conducted for 48 weeks.